Calibration and tuning method for mass spectrometer

Abstract

A method of calibrating and/or tuning a mass spectrometer includes the steps of: (i) providing a sample; (ii) producing ions from a surface of the sample by means of an ion-producing method, and (iii) using said ions to calibrate a mass spectrometer, tune a mass spectrometer or a combination thereof, wherein the ion producing method is desorption electrospray ionisation (DESI). A vacuum-deposited PLA glass slide can also be used as a calibration/tuning sample for any ion-producing method, e.g. DESI, MALDI or SIMS.

1 . A method of calibrating and/or tuning a mass spectrometer including the steps of:
 (i) providing a sample;   (ii) producing ions from a surface of the sample by means of an ion-producing method; and   (iii) using the ions to calibrate the mass spectrometer, tune the mass spectrometer or a combination thereof,   wherein the ion producing method is desorption electrospray ionisation (DESI).   
     
     
         2 . The method as claimed in  claim 1 , including steps preceding step (i) of:
 (a) producing ions by means of an ion-producing method which is DESI, and   (b) using the mass spectrometer to analyse the ions.   
     
     
         3 . The method as claimed in  claim 1 , including an additional step after step (iii) of:
 (iv) using the calibrated mass spectrometer to analyse ions produced by an ion-producing method which is DESI.   
     
     
         4 . The method as claimed in  claim 1 , wherein the sample is a homogeneous layer formed of a single type of molecule or a mixture of types of molecules. 
     
     
         5 . The method as claimed in  claim 1 , wherein the sample is a polyester. 
     
     
         6 . The method as claimed in  claim 1 , wherein the sample is a polylactic acid (PLA), 2,5-dihydroxybenzoic acid (2,5-DHB, monoisotopic mass: 154.02661), α-Cyano-4-hydroxycinnamic acid (CHCA, monoisotopic mass: 189.04259), caffeine (monoisotopic mass: 194.08038), rhodamine B (monoisotopic mass: 443.23347), angiotensin I (Angio I, monoisotopic mass: 1295.67749), or angiotensin II (Angio II, monoisotopic mass: 1045.53455). 
     
     
         7 . The method as claimed in  claim 6 , wherein the calibration sample is prepared by vacuum deposition, spray deposition or solvent deposition of molecules of interest. 
     
     
         8 . A method of calibrating and/or tuning a mass spectrometer including the steps of:
 (i) providing a sample;   (ii) producing ions from a surface of the sample by means of an ion-producing method; and   (iii) using the ions to calibrate the mass spectrometer, tune the mass spectrometer or a combination thereof,   wherein the sample comprises polylactic acid which has been vacuum-deposited onto glass.   
     
     
         9 . The method as claimed in  claim 8 , including steps preceding step (i) of:
 (a) producing ions by means of an ion-producing method, and   (b) using the mass spectrometer to analyse the ions.   
     
     
         10 . The method as claimed in  claim 8 , including an additional step after step (iii) of:
 (iv) using the calibrated mass spectrometer to analyse ions produced by an ion-producing method.   
     
     
         11 . The method as claimed in  claim 8 , wherein the ion producing methods are the same in every step. 
     
     
         12 . The method as claimed in  claim 8 , wherein the ion-producing methods independently include desorption electrospray ionisation (DESI), secondary ion mass spectrometry (SIMS) or matrix-assisted laser desorption ionisation (MALDI). 
     
     
         13 . The method as claimed in  claim 1 , including the step of determining the distribution of ions that are required to tune the mass spectrometer and providing a sample in step (i) which sample produces ions having the distribution as a result of the ion-producing method of step (ii). 
     
     
         14 . The method as claimed in  claim 13 , wherein the distribution of ions has a mass to charge ratio from 50 to 2000 m/z. 
     
     
         15 . The method as claimed in  claim 8 , including the step of determining the distribution of ions that are required to tune the mass spectrometer and providing a sample in step (i) which sample produces ions having the distribution as a result of the ion-producing method of step (ii). 
     
     
         16 . The method as claimed in  claim 15 , wherein the distribution of ions has a mass to charge ratio from 50 to 2000 m/z. 
     
     
         17 . The method as claimed in  claim 2 , including an additional step after step (iii) of:
 (iv) using the calibrated mass spectrometer to analyse ions produced by an ion-producing method which is DESI.